Water heater



FIG. 1 is a top, front, right side perspective view of a water heater in accordance with our design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a right side elevational view thereof; and,

FIG. 7 is a rear elevational view thereof. 

The ornamental design for water heater, as shown and described. 